remove duplicates from an unsorted array in java

I was asked in one of the interview that i recently appeared to remove duplicates from unsorted array while still maintaining the order in which they appeared.

For example:

int nums = [2,1,3,3,2,1,4]

int result = [2,1,3,4]

I tried two options one with Hashset and other with list. But i was still wondering if there is an better optimized solution to this.
Appreciate if you can help me out
NerdyHB

Here is are solution

public static void main(String args)
int nums = new int 2, 1, 3, 2, 1 ;
List<Integer> result = removeDuplicates(nums);
System.out.println(result);

int res = removeDuplicatesUsingHashSet(nums);
System.out.println(Arrays.toString(res));


public static List<Integer> removeDuplicates(int nums)
List<Integer> result = new ArrayList<>();
for (int n : nums)
if (!result.contains(n))
result.add(n);



return result;



public static int removeDuplicatesUsingHashSet(int nums)
HashSet<Integer> hset = new HashSet<>();
for (int n : nums)
hset.add(n);

int result = new int[hset.size()];
int counter = 0;
Iterator<Integer> itr = hset.iterator();
while (itr.hasNext())
result[counter++] = itr.next();


return result;



1 Answer
1

Change the line:

HashSet<Integer> hset = new HashSet<>();


to:

LinkedHashSet<Integer> hset = new LinkedHashSet<>();


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